Turnable breakdown voltage rf fet devices

ABSTRACT

A tunable breakdown voltage RF MESFET and/or MOSFET and methods of manufacture are disclosed. The method includes forming a first line and a second line on an underlying gate dielectric material. The second line has a width tuned to a breakdown voltage. The method further includes forming sidewall spacers on sidewalls of the first and second line such that the space between first and second line is pinched-off by the dielectric spacers. The method further includes forming source and drain regions adjacent outer edges of the first line and the second line, and removing at least the second line to form an opening between the sidewall spacers of the second line and to expose the underlying gate dielectric material. The method further includes depositing a layer of material on the underlying gate dielectric material within the opening, and forming contacts to a gate structure and the source and drain regions.

FIELD OF THE INVENTION

The invention relates to semiconductor structures and, moreparticularly, to tunable breakdown voltage RF MESFETs and MOSFETs andmethods of manufacture.

BACKGROUND

MESFETs (metal-semiconductor field effect transistor) and HEMTs (highelectron mobility transistors) are usually constructed in compoundsemiconductor technologies, and are faster but more expensive thansilicon-based JFETs or MOSFETs (metal-oxide-semiconductor field-effecttransistor). MESFETs are commonly used for microwave frequencycommunications and radar. For example, MESFETs/HEMTs can be used incascode circuits for cellular power amplifier applications. However, itis increasingly difficult to use MESFETs as the basis for integratedcircuits as the scale of integration increases, compared to CMOS siliconbased fabrication.

MOSFETs are typically used for amplifying or switching electronicsignals. MOSFETs are voltage-controlled power devices; that is, if nopositive voltage is applied between gate and source the MOSFET is alwaysnon-conducting (enhancement mode MOSFET). For depletion mode MOSFET, theMOSFET is conducting even if the applied voltage between gate and sourceis zero. Although the MOSFET is a four-terminal device with source (S),gate (G), drain (D), and body (B) terminals, the body (or substrate) ofthe MOSFET is often connected to the source terminal, making it athree-terminal device like other field-effect transistors.

SUMMARY

In an aspect of the invention, a method comprises forming a first lineand a second line on an underlying gate dielectric material. The secondline has a width tuned to a breakdown voltage. The method furthercomprises forming sidewall spacers on sidewalls of the first line andthe second line. The method further comprises forming source and drainregions adjacent outer edges of the first line and the second line. Themethod further comprises removing at least the second line to form anopening between the sidewall spacers of the second line and to exposethe underlying gate dielectric material. The method further comprisesdepositing a layer of material on the underlying gate dielectricmaterial within the opening. The method further comprises formingcontacts to a gate structure and the source and drain regions.

In an aspect of the invention, a method comprises: forming a gatedielectric material on a substrate; forming a first line and a secondline on the gate dielectric material; forming sidewall spacers on thefirst line and the second line, wherein the sidewall spacers between thefirst line and the second line define a minimum spacing, and thesidewall spacers pinch off the minimum spacing; forming source and drainregions adjacent outer edges of the first line and the second line;removing at least the second line to form an opening between thesidewall spacers of the second line and to expose the gate dielectricmaterial; depositing a layer of material on the gate dielectric materialwithin the opening; and forming contacts to a gate structure and thesource and drain regions.

In an aspect of the invention, a structure comprises: a gate dielectricmaterial on a substrate; a gate structure on the substrate; sidewallspacers on the gate structure and a sidewall structure remote from thegate structure forming an opening therebetween; a source region adjacentto the gate structure; a drain region remote from the gate structure andaligned with the sidewall structure; a layer of material on the gatedielectric material within the opening; and contacts to the gatestructure and the source and drain regions.

In another aspect of the invention, a design structure tangibly embodiedin a machine readable storage medium for designing, manufacturing, ortesting an integrated circuit is provided. The design structurecomprises the structures of the present invention. In furtherembodiments, a hardware description language (HDL) design structureencoded on a machine-readable data storage medium comprises elementsthat when processed in a computer-aided design system generates amachine-executable representation of the MESFETs and MOSFETs, whichcomprises the structures of the present invention. In still furtherembodiments, a method in a computer-aided design system is provided forgenerating a functional design model of the MESFETs and MOSFETs. Themethod comprises generating a functional representation of thestructural elements of the MESFETs and MOSFETs.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The present invention is described in the detailed description whichfollows, in reference to the noted plurality of drawings by way ofnon-limiting examples of exemplary embodiments of the present invention.

FIGS. 1-6 show processing steps and respective structures for formingMESFETs, in accordance with aspects of the present invention;

FIGS. 7-10 show processing steps and respective structures for formingMOSFETs, in accordance with aspects of the present invention; and

FIG. 11 is a flow diagram of a design process used in semiconductordesign, manufacture, and/or test.

DETAILED DESCRIPTION

The invention relates to semiconductor structures and, moreparticularly, to tunable breakdown voltage RF MESFETs and MOSFETs andmethods of manufacture. More specifically, the present invention isdirected to forming tunable breakdown voltage RF MESFETs and MOSFETs inCMOS process flows and resultant structures. The present invention isparticularly useful in manufacturing high breakdown voltage MESFETs usedin cascode circuits for cellular power amplifier (PA) applications,communication systems and test instruments. The methods of the presentinvention can also be used to manufacture other devices such as, forexample, RF LDMOS (laterally diffused metal oxide semiconductor) devicesor HEMTs.

Advantageously, the methods of forming the tunable breakdown voltageMESFET and/or MOSFET only use a single extra mask to defineindependently the gate length and gate-drain drift region. This providescircuit designers with great flexibility to tune the breakdown voltageof MESFET/MOSFET/LDMOS in a CMOS process flow in addition to theavailability of on-chip CMOS/BiCMOS devices. The methods of the presentinvention further provide the ability to have a self-align gate to bothsource and drain with adjustable gate-drain spacing (drift region). Themethods of the present invention also provide the ability to form avariable spacer with tight tolerances (e.g., no overlay tolerance, onlyedge lithography tolerance). More specifically, the present inventionprovides methods to form controllable spacer widths, space outsource/drain regions per poly crystalline (PC) line control, i.e.,providing controlled separation between gate and drain with no overlaytolerance, as well as the ability to have dual PC lines to PC line widthcontrol.

The structures of the present invention can be manufactured in a numberof ways using a number of different tools. In general, though, themethodologies and tools are used to form structures with dimensions inthe micrometer and nanometer scale. The methodologies, i.e.,technologies, employed to manufacture the structures of the presentinvention have been adopted from integrated circuit (IC) technology. Forexample, the structures of the present invention are built on wafers andare realized in films of material patterned by photolithographicprocesses on the top of a wafer. In particular, the fabrication of thestructures of the present invention uses three basic building blocks:(i) deposition of thin films of material on a substrate, (ii) applying apatterned mask on top of the films by photolithographic imaging, and(iii) etching the films selectively to the mask.

FIG. 1 shows a structure and respective processing steps in accordancewith aspects of the present invention. More specifically, the structure10 of FIG. 1 includes a substrate 12 with shallow trench isolation (STI)regions 14. In embodiments, the substrate 12 can be a BULK substrate orsilicon on insulator (SOI) substrate. In any scenario, the substrate cancomprise any semiconductor material such as, for example, Si, SiGe,GaAs, SiC, etc.

The STI regions 14 can be formed using conventional lithography, etchingand deposition methods. For example, a resist can be formed on thesubstrate 12, and exposed to energy (light) to form a pattern. Areactive ion etching (RIE) with appropriate chemistry is then performedto form trenches into the substrate 12. The trenches are then filledwith an insulator material, e.g., oxide, to form the STI regions 14. Inembodiments, any excess insulator material on the substrate 12 can beremoved using, for example, a chemical mechanical polishing (CMP)processes.

Still referring to FIG. 1, a gate dielectric material 16 is formed onthe substrate 12. In embodiments, the gate dielectric material 16 can bean oxide or other gate insulator material, e.g., hafnium based materialsor alumina, etc. The gate dielectric material 16 can be a thermallygrown oxide, or an oxide deposited using conventional depositionmethods, e.g., chemical vapor deposition (CVD) or atomic layerdeposition (ALD) or Molecular Beam Epitaxy (MBE). In embodiments, thethickness of the gate dielectric material 16 can vary from about 3 Å toa few hundred angstroms; although other dimensions are also contemplatedby the present invention.

Lines 18 and 20 are formed on the gate dielectric material 16, in a gateregion of a device. In embodiments, the lines 18 and 20 arepolycrystalline Si lines formed using conventional deposition,lithography and etching processes. For example, a polycrystalline Si isdeposited on the substrate 12 using conventional CVD processes,following by a patterning step using lithography and etching processesknown to those of skill in the art such that no further explanation isrequired for an understanding of the invention.

In embodiments, the height of the lines 18 and 20 can vary depending onthe technology node, with a preferred height of about 1000 Å to 2000 Å.The widths of the lines 18 and 20 can also be tuned, e.g., adjusted,depending on the technology node, with a preferred width of the line 18being about 10 nm to 500 nm, for a 14 nm node technology. Inembodiments, the width of line 18 defines the gate length; whereas, line20 can have a variable width for tuning breakdown voltage. The spacingbetween lines 18 and 20 can vary depending on spacer widths required fordifferent technologies, e.g., ranging from about 3 nm to several hundrednanometers.

In FIG. 2, spacers 22 a and 22 b are formed on sides of the lines 18 and20. In embodiments, the spacers 22 a and 22 b can be, for example,oxide, nitride, oxynitride, or other stacked materials. In embodiments,the spacers 22 a and 22 b can be formed by conventional deposition andetching processes. For example, a blanket deposition of material can beformed on the gate dielectric material 16 and lines 18 and 20. Thematerial should be deposited to such dimensions that ensure the spacebetween the lines 18 and 20 is pinched off, thus defining the requiredminimum spacing between the lines 18 and 20. The material then undergoesan anisotropic etching process to remove it from all horizontalsurfaces.

Still referring to FIG. 2, source and drain regions 24 are formed usingconventional ion implantation or doping processes. The source and drainregions 24 are self aligned to the lines 18 and 20, e.g., using thespacers 22 a and 22 b. More specifically, the source and drain regions24 are adjacent outer edges of the first line 18 and the second line 20and more specifically the spacers 22 a and 22 b formed thereon. Inembodiments, reference numeral 24 can also represent conventionalextension and halo implant processes. Lines 18 and 20 can also be maskedusing a dielectric material, e.g., oxide or nitride, to prevent the S/Dor other implants from implanting the lines.

For MESFET processes, in FIG. 3, a resist 28 is formed on substrate 12,with its pattern exposing the lines 18 and 20. In embodiments, theresist boundary is formed on the outermost spacers 22 a and 22 b.Accordingly, the spacers 22 a and 22 b are designed to be sufficientlythick in order to have the resist boundary land thereon. The lines 18and 20 are then removed using conventional etching processes, e.g., RIEor a wet etch, selective to its material.

In FIG. 4, the resist is removed and a nitride layer 30 is conformallyformed on the structure. More specifically, in embodiments, the resistcan be removed by, for example, an oxygen ashing process or other knownstripping method. The nitride layer 30 is formed by a CVD conformaldeposition process over the exposed portions of the spacers 22 a and 22b, and the gate dielectric material 16. In embodiments, the nitridelayer 30 can be an oxynitride or other blocking material.

In FIG. 5, portions of the nitride layer 30 and gate dielectric material16 are removed using conventional lithography and etching processes. Forexample, a resist is deposited and subsequently patterned to exposeportions of the nitride layer 30 over at least the STI regions 14,source and drain regions 24 and the space 18 a formed by the removal ofline 18. The resist will protect all other regions including the nitridematerial 30 between the sidewall spacers 22 b, 22 b, e.g., the space 20a formed by the removal of line 20. This space can be adjusted in orderto tune the voltage breakdown, for different capabilities. An etchingprocess (RIE or wet etch) is then performed to remove the exposednitride layer 30 and underlying gate dielectric material 16. Inembodiments, two different etching processes with different chemistriescan be performed to remove these separate materials, e.g., nitride layer30 and gate dielectric material 16. The resist can then be removed byconventional processes as described herein.

Still referring to FIG. 5, silicide regions 32 are formed in contactwith the source and drain regions 24. Also, a silicide region is formedas the gate structure 32 a for a MESFET. As shown in FIG. 5, the gatestructure 32 a is spaced away (e.g., remote) from the source region 24to prevent shorting. In embodiments, the silicide regions 32 and gatestructure 32 a are formed by deposition of a metal and a subsequentannealing process. In embodiments, the metal material can be, forexample, titanium, cobalt, nickel, platinum or other known metals ormetal alloys or combinations thereof. The metal material can bedeposited to a thickness of about 300 Å to about 1000 Å; although otherdimensions are also contemplated by the present invention. The annealprocess can be a conventional anneal, e.g., ranging from a few secondsto a several minutes at temperatures of about 300° C. to 1000° C. Asshould be understood by those of skill in the art, the source and drainregions 24 are both self-aligned to the gate 32 a, and drain to gatedistance (e.g., space 20 a) can be tuned based on the width of the line20 which is removed in subsequent processing steps.

FIG. 6 shows further processing steps and a respective structure inaccordance with aspects of the present invention. In particular, in FIG.6, contacts 34 and wiring structures 36 are formed in direct electricalcontact with the silicide regions 32 and gate structure 32 a. Thecontacts 34 and wiring structures 36 are formed by conventional CMOSprocesses. For example, interlevel dielectric material (ILD) 38 isdeposited and patterned using conventional lithography and etching (RIE)processes. The ILD 38 can be back end of the line (BEOL) materials suchas Borophosphosilicate glass (BSPG) or undoped silicate glass (USG).After via formation, metal material e.g., copper or aluminum, isdeposited in the vias and any excess material is removed from a surfaceof the ILD 38 using, e.g., CMP processes. The wiring structure 36 canthen be formed by a deposition and patterning processes.

FIGS. 7-10 show processing steps and respective structures for theformation of a MOSFET in accordance with aspects of the presentinvention. Referring to FIG. 7, a resist 28 is formed on substrate 12,with its pattern exposing line 20 (shown in FIG. 2). In embodiments, theresist boundary covers the line 18 and the outermost spacer 22 b,thereby protecting the line 18 during etching processes. The line 20 isthen removed using conventional etching processes, e.g., RIE or wetetch, selective to its material. Line 18 and the underlying gatedielectric material 16 will form a gate structure.

In FIG. 8, the resist is removed and a nitride layer 30 is conformallyformed on the structure and a dielectric layer 25 is also over line 18.More specifically, in embodiments, the resist can be removed by, forexample, an oxygen ashing process or other known stripping method. Thenitride layer 30 is formed by a CVD conformal deposition process overthe exposed portions of the spacers 22 a and 22 b, and the gatedielectric material 16. In embodiments, the nitride layer 30 can be anoxynitride or other blocking material.

In FIG. 9, portions of the nitride layer 30 and gate dielectric material16 are removed on the horizontal surfaces using conventional lithographyand etching processes. For example, a resist is deposited andsubsequently patterned to expose portions of the nitride layer 30 overat least the STI regions 14, source and drain regions 24 and the line18. The resist will protect all other regions including the nitridematerial 30 between the sidewall spacers 22 b, 22 b, e.g., the space 20a formed by the removal of line 20. An etching process (RIE) is thenperformed to remove the exposed portions of the nitride layer 30 andunderlying gate dielectric material 16. In embodiments, two differentetching processes with different chemistries can be performed to removethese separate materials, e.g., nitride layer 30 and gate dielectricmaterial 16. The resist can then be removed by conventional processes asdescribed herein.

Still referring to FIG. 9, silicide regions 32 are formed in contactwith the source and drain regions 24 and line (gate structure) 18. Inembodiments, the silicide regions 32 are formed by deposition of a metaland a subsequent annealing process. In embodiments, the metal materialcan be, for example, titanium, cobalt, nickel, platinum or other knownmetals or metal alloys or combinations thereof. The metal material canbe deposited to a thickness of about 300 Å to about 1000 Å; althoughother dimensions are also contemplated by the present invention. Theanneal process can be a conventional anneal, e.g., ranging from a fewseconds to a several minutes at temperatures of about 300° C. to 1000°C. As should be understood by those of skill in the art, the source anddrain regions 24 are both self-aligned to the gate 32 a, and drain togate distance (e.g., space 20 a) can be tuned based on the width of theline 20 which is removed in subsequent processing steps.

In FIG. 10, contacts 34 and wiring structures 36 are formed in directelectrical contact with the silicide regions 32. The contacts 34 andwiring structures 36 are formed by conventional CMOS processes asalready described herein.

FIG. 11 is a flow diagram of a design process used in semiconductordesign, manufacture, and/or test. FIG. 11 shows a block diagram of anexemplary design flow 900 used for example, in semiconductor IC logicdesign, simulation, test, layout, and manufacture. Design flow 900includes processes, machines and/or mechanisms for processing designstructures or devices to generate logically or otherwise functionallyequivalent representations of the design structures and/or devicesdescribed above and shown in FIGS. 1-10. The design structures processedand/or generated by design flow 900 may be encoded on machine-readabletransmission or storage media to include data and/or instructions thatwhen executed or otherwise processed on a data processing systemgenerate a logically, structurally, mechanically, or otherwisefunctionally equivalent representation of hardware components, circuits,devices, or systems. Machines include, but are not limited to, anymachine used in an IC design process, such as designing, manufacturing,or simulating a circuit, component, device, or system. For example,machines may include: lithography machines, machines and/or equipmentfor generating masks (e.g. e-beam writers), computers or equipment forsimulating design structures, any apparatus used in the manufacturing ortest process, or any machines for programming functionally equivalentrepresentations of the design structures into any medium (e.g. a machinefor programming a programmable gate array).

Design flow 900 may vary depending on the type of representation beingdesigned. For example, a design flow 900 for building an applicationspecific IC (ASIC) may differ from a design flow 900 for designing astandard component or from a design flow 900 for instantiating thedesign into a programmable array, for example a programmable gate array(PGA) or a field programmable gate array (FPGA) offered by Altera® Inc.or Xilinx® Inc.

FIG. 11 illustrates multiple such design structures including an inputdesign structure 920 that is preferably processed by a design process910. Design structure 920 may be a logical simulation design structuregenerated and processed by design process 910 to produce a logicallyequivalent functional representation of a hardware device. Designstructure 920 may also or alternatively comprise data and/or programinstructions that when processed by design process 910, generate afunctional representation of the physical structure of a hardwaredevice. Whether representing functional and/or structural designfeatures, design structure 920 may be generated using electroniccomputer-aided design (ECAD) such as implemented by a coredeveloper/designer. When encoded on a machine-readable datatransmission, gate array, or storage medium, design structure 920 may beaccessed and processed by one or more hardware and/or software moduleswithin design process 910 to simulate or otherwise functionallyrepresent an electronic component, circuit, electronic or logic module,apparatus, device, or system such as those shown in FIGS. 1-10. As such,design structure 920 may comprise files or other data structuresincluding human and/or machine-readable source code, compiledstructures, and computer-executable code structures that when processedby a design or simulation data processing system, functionally simulateor otherwise represent circuits or other levels of hardware logicdesign. Such data structures may include hardware-description language(HDL) design entities or other data structures conforming to and/orcompatible with lower-level HDL design languages such as Verilog andVHDL, and/or higher level design languages such as C or C++.

Design process 910 preferably employs and incorporates hardware and/orsoftware modules for synthesizing, translating, or otherwise processinga design/simulation functional equivalent of the components, circuits,devices, or logic structures shown in FIGS. 1-10 to generate a netlist980 which may contain design structures such as design structure 920.Netlist 980 may comprise, for example, compiled or otherwise processeddata structures representing a list of wires, discrete components, logicgates, control circuits, I/O devices, models, etc. that describes theconnections to other elements and circuits in an integrated circuitdesign. Netlist 980 may be synthesized using an iterative process inwhich netlist 980 is resynthesized one or more times depending on designspecifications and parameters for the device. As with other designstructure types described herein, netlist 980 may be recorded on amachine-readable data storage medium or programmed into a programmablegate array. The medium may be a non-volatile storage medium such as amagnetic or optical disk drive, a programmable gate array, a compactflash, or other flash memory. Additionally, or in the alternative, themedium may be a system or cache memory, buffer space, or electrically oroptically conductive devices and materials on which data packets may betransmitted and intermediately stored via the Internet, or othernetworking suitable means.

Design process 910 may include hardware and software modules forprocessing a variety of input data structure types including netlist980. Such data structure types may reside, for example, within libraryelements 930 and include a set of commonly used elements, circuits, anddevices, including models, layouts, and symbolic representations, for agiven manufacturing technology (e.g., different technology nodes, 32 nm,45 nm, 90 nm, etc.). The data structure types may further include designspecifications 940, characterization data 950, verification data 960,design rules 970, and test data files 985 which may include input testpatterns, output test results, and other testing information. Designprocess 910 may further include, for example, standard mechanical designprocesses such as stress analysis, thermal analysis, mechanical eventsimulation, process simulation for operations such as casting, molding,and die press forming, etc. One of ordinary skill in the art ofmechanical design can appreciate the extent of possible mechanicaldesign tools and applications used in design process 910 withoutdeviating from the scope and spirit of the invention. Design process 910may also include modules for performing standard circuit designprocesses such as timing analysis, verification, design rule checking,place and route operations, etc.

Design process 910 employs and incorporates logic and physical designtools such as HDL compilers and simulation model build tools to processdesign structure 920 together with some or all of the depictedsupporting data structures along with any additional mechanical designor data (if applicable), to generate a second design structure 990.

Design structure 990 resides on a storage medium or programmable gatearray in a data format used for the exchange of data of mechanicaldevices and structures (e.g. information stored in a IGES, DXF,Parasolid XT, JT, DRG, or any other suitable format for storing orrendering such mechanical design structures). Similar to designstructure 920, design structure 990 preferably comprises one or morefiles, data structures, or other computer-encoded data or instructionsthat reside on transmission or data storage media and that whenprocessed by an ECAD system generate a logically or otherwisefunctionally equivalent form of one or more of the embodiments of theinvention shown in FIGS. 1-10. In one embodiment, design structure 990may comprise a compiled, executable HDL simulation model thatfunctionally simulates the devices shown in FIGS. 1-10.

Design structure 990 may also employ a data format used for the exchangeof layout data of integrated circuits and/or symbolic data format (e.g.information stored in a GDSII (GDS2), GL1, OASIS, map files, or anyother suitable format for storing such design data structures). Designstructure 990 may comprise information such as, for example, symbolicdata, map files, test data files, design content files, manufacturingdata, layout parameters, wires, levels of metal, vias, shapes, data forrouting through the manufacturing line, and any other data required by amanufacturer or other designer/developer to produce a device orstructure as described above and shown in FIGS. 1-10. Design structure990 may then proceed to a stage 995 where, for example, design structure990: proceeds to tape-out, is released to manufacturing, is released toa mask house, is sent to another design house, is sent back to thecustomer, etc.

The method(s) as described above is used in the fabrication ofintegrated circuit chips. The resulting integrated circuit chips can bedistributed by the fabricator in raw wafer form (that is, as a singlewafer that has multiple unpackaged chips), as a bare die, or in apackaged form. In the latter case the chip is mounted in a single chippackage (such as a plastic carrier, with leads that are affixed to amotherboard or other higher level carrier) or in a multichip package(such as a ceramic carrier that has either or both surfaceinterconnections or buried interconnections). In any case the chip isthen integrated with other chips, discrete circuit elements, and/orother signal processing devices as part of either (a) an intermediateproduct, such as a motherboard, or (b) an end product. The end productcan be any product that includes integrated circuit chips, ranging fromtoys and other low-end applications to advanced computer products havinga display, a keyboard or other input device, and a central processor.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A structure comprising: a gate dielectricmaterial on a substrate; a gate structure on the substrate; sidewallspacers on the gate structure and a sidewall structure remote from thegate structure forming an opening therebetween; a source region adjacentto the gate structure; a drain region remote from the gate structure andaligned with the sidewall structure; a layer of material on the gatedielectric material within the opening; and contacts to the gatestructure and the source and drain regions.
 2. The structure of claim 1,wherein the gate structure is a silicide between the two sidewallspacers, and the source region is separated from the gate structure. 3.The structure of claim 1, wherein the gate structure is a poly line andthe gate dielectric material is abutting the gate structure.
 4. Thestructure of claim 1, further comprising silicide on the source anddrain regions and the gate structure, under the contacts.
 5. Thestructure of claim 1, wherein the source region is formed remotely fromthe gate structure.
 6. The structure of claim 1, wherein the source anddrain regions are self aligned.
 7. The structure of claim 1, wherein aspace between the gate structure and the drain region is controlled byline lithography with no overlay tolerance.
 8. The structure of claim 1,wherein the substrate is silicon on insulator (SOI) substrate.
 9. Thestructure of claim 1, wherein the gate dielectric material is formedunder the sidewall spacers.
 10. The structure of claim 1, furthercomprising a nitride layer over the gate dielectric material.
 11. Thestructure of claim 1, further comprising silicide regions formed incontact with the source and drain regions, wherein the gate structure isspaced away from the source region to prevent shorting.
 12. Thestructure of claim 11, wherein a portion of the silicide regions formthe gate structure.
 13. The structure of claim 12, wherein the contactsand wiring structures are formed in direct electrical contact with thesilicide regions and gate structure.